Some of my favorite pranks involve office computers.
At one facility where I was employed in their maint. department I did a lot of their network wiring...
Needless to say being tight with the IT person helps a lot with these pranks...

I already did the classic take a photo of the desktop, set that image as your wallpaper, hide the icons and taskbar. She was confused for 10 minutes. She just thought the computer froze. I like that one.

I already did the classic take a photo of the desktop, set that image as your wallpaper, hide the icons and taskbar. She was confused for 10 minutes. She just thought the computer froze. I like that one.

Thats another good one but the blue screen of death brings out an increased pucker factor...

Another good one is if the IT person upon seeing the blue screen wheels up with an old clunker of a pc and pretends that the victim will have to use that while theirs is being repaired...